Quality Assurance 



The operation of the HRGC/HRMS was evaluated each day 

 by analyzing standard mixtures of PCDD/PCDF isomers. These 

 mixtures consisted of 2 , 3 , 7, 8-tetra-CDD, 2 , 3 , 7 , 8-tetra-CDF, 

 2,3,7,8-tetra-CDD-13c3^2/ and 2 , 3 , 7 , 8-tetra-CDF-13c3^2 to evaluate 

 accuracy of quantification and to evaluate isomer resolution. 

 Mixtures of selected PCDD/PCDF isomers were used to evaluate the 

 stability of the chromatographic elution windows. The mass focus 

 accuracy of the MID unit was evaluated before each analysis by 

 observing selected ion masses from perfluorokerosene (PFK) . 

 Adjustments were made to the offset to correct for minor 

 variations. Mass focus stability was assured by use of a 

 reference PFK "lock mass" to correct for any mass focus drift. 



Native spike and a laboratory method blank samples were 

 processed during the extraction and cleanup of the samples. For 

 the native spike, isotopically labeled compounds were added to 

 the Soxhlet thimble with no sediment added. The compounds and 

 amounts added are listed in Table 4. The native spike samples 

 were used to evaluate the accuracy of quantification, while the 

 laboratory method blanks were used to demonstrate freedom from 

 contamination. The results of these analyses are summarized in 

 Table 4. The analyses of the method blanks were free of 

 PCDD/PCDF contamination except for traces of hepta- and octa- 

 CDD/CDF. 



Recovery of the spiked PCDD/PCDF standards from the 

 native spike samples ranged from 62-110 percent, which is within 

 the expected range of variation for a sample subjected to 

 florisil chromatography. Replicate analyses were not done as 

 part of this study, but the precision of these analyses are 

 generally about ± 20-30%. 



Recoverv of Internal Standards 



Recoveries of the internal standards, 2 , 3 , 7, 8-tetra- 

 CDD-L JCi2 ' 1,2,3,7, 8-penta-CDD-13c-L2 , 1,2,3,6,7, 8-hexa-CDD-13c3^2 . 

 1,2,3,4,6,7, 8-hepta-CDD--'-3c^2 , 1,2,3,4,6,7,8, 9-octa-CDD-13c, 3 , 

 2,3,7, 8-tetra-CDF-13c-L2 , 1,2,3,7, 8-penta-CDF-13c-L2 / 1,2,3,4,7,8- 

 hexa-CDF-LJCi2 and 1, 2 , 3 , 4 , 6, 7 , 8-hepta-CDF-13c3^2 were calculated 

 by comparison to the external standard, 1, 2, 3 , 4-tetra-CDD-12C]^2 ' 

 which was added following extraction. Relative response factors 

 were _ determined from four analyses of a standard mixture 

 containing the eight isotopically labelled standards. The 

 equation used to calculate the recoveries was: 



Recovery (%) = Ais x Ors x 100 

 Ars X Qis X Rf 



